Watch Glenn Hughes Join David Coverdale Onstage for a Deep Purple Song

The audience at Whitesnake's June 9 tour stop in Beverly Hills received a welcome surprise when Glenn Hughes, frontman David Coverdale's former bandmate in Deep Purple, stopped by to lend his vocals to a performance of the Purple classic "Lay Down, Stay Down."

Hughes, who's juggling his own extensive tour commitments between dates with the Kings of Chaos and a long list of upcoming solo shows, joins Coverdale in the fan-shot footage above — which offers a slight hint of what might have been if Coverdale had been successful in persuading Ritchie Blackmore to participate in the Deep Purple tribute project that eventually morphed into Whitesnake's recent The Purple Album.

While Coverdale is approachingThe Purple Album as the project that might serve as his "farewell to the big rock stuff," Hughes is moving on from the breakup of his latest band, California Breed, by prepping a new solo effort that he predicts will be in stores sometime in early 2016.

"I write songs every moment of the day. I have been writing songs for a solo album," Hughes revealed in a recent interview. "I am going to make a solo album this year. It will be released next year. I can't say when I'm gonna record it, because I'm very busy, but I can say this to you: by the end of this year, the album will be finished and mastered, and the artwork will be done, and it will be coming out early next year."